An hermetic electric compressor including an electric element and a compressing element in a closed vessel is widely used as a compressor employed in an electric refrigerator or an air conditioner. For example, an hermetic electric compressor having a structure shown in FIG. 6 is disclosed as prior art in U.S. Pat. No. 5,228,843.
The conventional hermetic electric compressor will be described hereinafter with reference to FIG. 6. The upside and downside of the hermetic electric compressor are determined with reference to the state where the compressor is installed in the normal attitude.
FIG. 6 is a sectional view of the conventional hermetic electric compressor. Closed vessel 201 includes stator 202, electric element 204 formed of rotor 203, and compressing element 205 driven by electric element 204. Oil 207 is reserved in the lower part of closed vessel 201. Compressing element 205 will now be described in detail. Crankshaft 208 has spindle 209 pressed and fitted to rotor 203 and eccentric part 210 formed eccentrically to spindle 209. Oil pump 211 is disposed in spindle 209 so as to open in oil 207. One end of communication hole 212 disposed in eccentric part 210 opens at the upper end of eccentric part 210, and the other end communicates with oil pump 211 via oil groove 213 formed in the outer periphery of spindle 209. Cylinder block 214 has substantially cylindrical compression chamber 215 and bearing 216 for pivoting spindle 209, and is formed over electric element 204. Piston 217 is inserted into compression chamber 215, and is coupled to eccentric part 210 through coupling means 218. Valve plate 219 having a compressing valve and a suction valve is disposed on an end surface of compression chamber 215, and head 220 having a space partitioned to a discharge side and a suction side is disposed outside valve plate 219. Suction tube 221 is fixed to closed vessel 201 and connected to the low pressure side (not shown) of a freezing cycle so that refrigerant gas (not shown) is guided into closed vessel 201. Suction muffler 222 is disposed under cylinder block 214, and is grappled and hence fixed by valve plate 219 and head 220. One end of suction muffler 222 communicates with the suction side of head 220 and communicates with compression chamber 215 through the suction valve of valve plate 219. The other end of suction muffler 222 forms sound absorbing space 224 communicating with opening 223 formed near suction tube 221 disposed in closed vessel 201.
A series of operations in the structure discussed above are described. Rotor 203 of electric element 204 rotates crankshaft 208. Motion of eccentric part 210 is transmitted to piston 217 via coupling means 218, thereby reciprocating piston 217 in compression chamber 215. Refrigerant gas guided into closed vessel 201 through suction tube 221 is sucked from opening 223 of suction muffler 222, and is continuously compressed in compression chamber 215. By rotating crankshaft 208, oil 207 is sucked by oil pump 211, is guided upwardly from oil groove 213, passes through communication hole 212, and is sprayed from the upper end of eccentric part 210 into closed vessel 201. Sprayed oil 207 is sucked together with refrigerant gas from opening 223 of suction muffler 222, and provides lubrication and sealing between piston 217 and the inside of compression chamber 215.
However, the hermetic electric compressor has the following problems. In the conventional hermetic electric compressor, oil 207 sprayed into closed vessel 201 is indirectly sucked together with refrigerant gas from opening 223, so that an amount of oil 207 sucked into compression chamber 215 is widely dispersed by spraying oil 207. Therefore, when the amount of oil 207 is small, lubrication between piston 217 and the inside of compression chamber 215 is insufficient, thereby leading to the generation of abrasion of sliding parts, and sealing is incomplete thereby decreasing freezing capacity.
The present invention addresses the conventional problems, and aims to provide an hermetic electric compressor capable of stably supplying the right amount of oil into a compression chamber.